When using from_raw_data in PynamoDB, you have to pass in the DynamoDB dict structure ({"attribute_name": {"S": "value"}), not a plain dictionary. When 6.0.0 comes out, there will be to_dict and from_dict methods.
Until to_dict and from_dict are released, use this to convert a Pynamo object to a dictionary:
found_record_dict = found_record.__dict__.get("attribute_values", found_record.__dict__)